A vehicle comprises a motor (4) and a wet clutch (12) for transmission of
torque output of the motor to road wheels of the vehicle and transmission
of road load from the road wheels to the motor (4). The wet clutch is
disengaged in response to a clutch disengagement control signal.
Accounting for clutch drag state of the wet clutch, a controller (8)
selects one out of various values as threshold (Voff). The controller (8)
determines that the wet clutch be disengaged when a parameter indicative
of the actual vehicle speed has a predetermined relationship with the
threshold. The controller (20) generates the clutch disengagement control
signal upon determining that the wet clutch be disengaged.